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GET_NPROCS(3) Linux Programmer's Manual GET_NPROCS(3)

NAME

     get_nprocs, get_nprocs_conf - get number of processors

SYNOPSIS

     #include <sys/sysinfo.h>

     int get_nprocs(void);
     int get_nprocs_conf(void);

DESCRIPTION

     The function get_nprocs_conf() returns the number of processors config-
     ured by the operating system.

     The function get_nprocs() returns the number  of  processors  currently
     available  in the system.  This may be less than the number returned by
     get_nprocs_conf() because processors may be offline (e.g., on  hotplug-
     gable systems).

RETURN VALUE

     As given in DESCRIPTION.

ATTRIBUTES

     For   an   explanation   of   the  terms  used  in  this  section,  see
     attributes(7).

     allbox; lb lb lb l l l.  Interface Attribute Value T{ get_nprocs(),
     get_nprocs_conf() T}   Thread safety  MT-Safe

CONFORMING TO

     These functions are GNU extensions.

NOTES

     The current implementation of  these  functions  is  rather  expensive,
     since  they  open and parse files in the /sys filesystem each time they
     are called.

     The following sysconf(3) calls make use of the functions documented  on
     this page to return the same information.

         np = sysconf(_SC_NPROCESSORS_CONF);     /* processors configured */
         np = sysconf(_SC_NPROCESSORS_ONLN);     /* processors available */

EXAMPLE

     The following example shows how get_nprocs() and get_nprocs_conf()  can
     be used.

     #include <stdlib.h> #include <stdio.h> #include <sys/sysinfo.h>

     int main(int argc, char *argv[]) {
         printf("This system has %d processors configured and "
                 "%d processors available.\n",
                 get_nprocs_conf(), get_nprocs());
         exit(EXIT_SUCCESS); }